Solar panel junction box capable of integratingwith a variety of accessory modules, and method of use

ABSTRACT

A junction box is affixed to, and electrically coupled with, a solar panel. The junction box is configured to releaseably engage and disengage accessory modules, thereby allowing accessory modules to be replaced or exchanged easily. Accessory modules are electrically coupled with other accessory modules in the solar panel string. The furthest downstream accessory module is connected to a wire harness, which is connected to a central combiner box.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of, and claims the benefitof, U.S. application Ser. No. 13/761,532, having a filing date of Feb.7, 2013.

BACKGROUND

(1) Field

The present invention relates generally to electrical control systemsfor use in the solar industry and, more particularly, to junction boxesthat facilitate “plug and play” functionality of solar energy accessorymodules.

(2) Related Art

The invention discussed herein can be used with connectors disclosed inU.S. patent application Ser. No. 12/502,395, pertaining to “Low LeakageElectrical Joints and Wire Harnesses, and Method of Making the Same”,that was filed on Jul. 14, 2009, and issued on Dec. 10, 2013 as U.S.Pat. No. 8,604,342 B2, which is hereby incorporated by reference.

Due to technological advances, increased costs of non-renewableresources, and governmental incentives, solar energy can now be aneconomically advantageous endeavor. Accordingly, interest in solarenergy has surged, and innovators are constantly developing new systemsand components to optimize energy collection because variables such asinconsistent sunlight, breakage and malfunction outages in the solarfield, and other fluctuations greatly affect the operating environment.

Considerable progress in optimization has been achieved by thedevelopment and refinement of various “accessory modules”. In short,accessory modules are electrical components added onto conventionaljunction boxes to perform functions such as lessening peaks and valleysin energy generation, Maximum Power Point Tracking (“MPPT”), and toallow for direct AC conversion, including that achieved bymicro-inverters. To achieve this, one junction box is outfitted with oneaccessory module, so the solar panels associated with that specificjunction box are mediated by that specific accessory module.

While employing accessory modules is definitely an improvement over notusing accessory modules, the one-module-per-group-of-panels arrangementdoes not permit optimization of the individual panels. This isundesirable because individual panels in a group may exist in differentmicroenvironments. For example, one panel might be partially shadedwhile another panel is not. Accordingly, the optimization of individualpanels would be most beneficial.

Optimizing individual panels, however, has been impractical orundesirable up until now. Specifically, coupling a panel to an accessorymodule requires affixing and hard wiring them together. As a result,when a panel or accessory module is damaged, destroyed, or otherwisequits working properly, the panel and accessory module are more-or-lesspermanently stuck together, and the entire assembly must be replaced.Alternatively, extensive time and labor is expended to separate the goodhardware from the bad. Moreover, if it is desirable to swap out oneaccessory module for another (for example due to seasonal sunlightchanges) one must swap the entire panel. This makes the optimization ofindividual panels impractical.

In view of the aforementioned limitations, it is desirable to have adevice that allows an individual solar panel to be easily, expeditiouslyand reversibly outfitted with an accessory module.

Thus, there remains a need for a new and improved solar panel junctionbox capable of integrating with a variety of accessory modules, and themethod of using this junction box.

SUMMARY OF THE INVENTIONS

The present invention is directed to a universal junction box that isaffixed to a solar panel and replaces the conventional junction box anddownstream accessory module box. The junction box is configured toreleaseably engage and disengage accessory modules which employ astandard engagement interface, thereby facilitating the replacement ofone accessory module for another, for whatever reason, without having toreplace or move the associated panel.

The junction box is electrically connected to the associated solar panelby the panel's electrical ribbon. Individual panels in a string areconnected to each other in series only through wire connectors of theaccessory modules. The furthest downstream accessory module is connectedto a wire harness, which is connected to a central combiner box.

One aspect of the present inventions is to provide a device that can besubstantially permanently affixed to a solar panel.

Another aspect is that this device releaseably engages and disengages anaccessory module, thereby allowing accessory modules to be replaced andchanged with minimal effort, time, danger or damage.

Another aspect is that this device is compatible with preexistingaccessory module interfaces.

Another aspect is that this device provides functionality beyond asimple docking station, for example by acting as a junction box.

Another aspect is that this device is configured to quickly and easilyinterconnect with other panels in a string.

Another aspect is that this device is compatible with preexistingconnectors, plugs, implements and accessories.

Another aspect is that this device can be used for retrofitting existingpanels, or can be coupled with newly manufactured panels.

Another aspect is that this device is safe, cost effective, electricallyefficient and not labor or capital intensive to manufacture, deliver orinstall.

These and other aspects of the present inventions will become apparentto those skilled in the art after a reading of the following descriptionof the preferred embodiment when considered with the drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 schematically represents a string of solar panel control systems;

FIG. 2 is a perspective view of a junction box;

FIG. 3 is a plan view of a junction box;

FIG. 4 is a side view of a junction box;

FIG. 5 is a plan view of a junction box with the lids removed to showstructures beneath;

FIG. 6 is a cross-sectional plan view of a junction box, taken along B-Bof FIG. 4;

FIG. 7 is an end view of a junction box;

FIG. 8 is a cross-sectional side view of a junction box, taken along A-Aof FIG. 3;

FIG. 9 represents a bottom view of an accessory module schematicallyrepresenting where an input could be plugged in;

FIG. 10 schematically represents how an accessory module is engaged witha junction box, with the raised strips of the accessory module shown inphantom; and

FIG. 11 schematically represents an accessory module engaged with ajunction box, with certain accessory module structures shown in phantom.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, like reference characters designate likeor corresponding parts throughout the several views.

The following reference characters apply:

-   10—Junction box-   13—Engagement platform-   15—Base assembly-   16—Air vent-   17—Groove-   18—Recess-   19—Securing rib-   20—Socket terminal assembly-   22—Front surface-   23—Back surface-   27—Ribbon terminals-   28—Ribbon-   30—Removable lid-   35—Diode cover-   40—Female module plug-   41—O-ring-   42—Female Module terminal-   45—Diode assembly module-   46—Diode-   60—Solar array-   65—String-   70—Solar panel-   80—Wire harness-   90—Accessory Module-   92—Male module plug-   94—Clipping assembly-   95—Alignment ribs-   96—Input-   97—Output-   98—Wire connector-   99—Wire plug-   100—Solar panel control system

Referring now to the drawings, it will be understood that theillustrations describe a preferred embodiment of the invention, but arenot intended to limit the inventions thereto.

An overview of solar array 60 is schematically depicted in FIG. 1, whichpreferably includes between 6 and 8 solar panels 70 in string 65, eachsolar panel 70 including one junction box 10, with each junction box 10engaged to and in communication with one accessory module 90. Theresulting assembly of accessory module 90/junction box/solar panel 70 issolar panel control system 100.

Each accessory module 90 is electrically connected to another accessorymodule 90. Solar panels 70 are those conventionally used in small- andindustrial scale solar energy systems, with an example of a suitablepanel being E237 from SunPower Corporation of San Jose, Calif.

The most downstream junction box 10 (bottom left) in string 65 isconnected by wire harness 80 to “COMBINER”. Wire harness 80 ispreferably the device disclosed in U.S. patent application Ser. No.12/502,395, filed on Jul. 14, 2009, issued on Dec. 10, 2013 as U.S. Pat.No. 8,604,342 B2, and which is incorporated herein. FIG. 1 depicts wireharness 80 accommodating 6 strings 65 (one string 65 plus 5 “bolts”representing other strings) but between 3 and 64 strings can beaccommodated by wire harness 80. All strings 65 (and associatedcomponents such as solar panels 70) in one wire harness 80 collectivelyform solar array 60.

Downstream from COMBINER BOX is FUSE BOX, INVERTER and SWITCH YARD. Aswould be understood by one of ordinary skill, the combiner wouldactually accommodate multiple wire harnesses 80, the fuse box wouldactually accommodate multiple combiners, the inverter would actuallyaccommodate multiple fuse boxes, and the switch yard would actuallyaccommodate multiple inverters. However, redundant assemblies have beenomitted for simplicity. The person of ordinary skill would alsounderstand that the depiction merely represents some major components inone possible system.

One junction box 10 is affixed to each solar panel 70, preferably by anadhesive such as PV 804 from Dow Corning of Midland, Mich., althoughother adhesives, or standard methods of attaching would be suitable.Back surface 23 (shown in FIG. 4) is adhered to solar panel 70. WhileFIG. 1 schematically depicts junction boxes 10 on the side of solarpanels 70, it is possible to affix junction box 10 in other locations,preferably on solar panel 70 itself, so long as front surface 22 (FIG.4) is accessible to permit engagement of accessory modules 90, and topermit connection of junction box 10 to solar panel 70 by ribbon 28.FIG. 1 depicts six solar panels 70 of string 65 in series, but it wouldalso be possible to orient them in parallel.

Referring now to FIG. 2, junction box 10 is constructed on base assembly15 and can be conceptualized as having the electrical “brains” in theupper half, and the physical “module interface” in the lower half.Externally on the upper half is removable lid 30 which, as the nameimplies, is removable. Externally below removable lid 30 is diode cover35, which is not removable. Removable lid 30 and diode cover 35 protectthe electrical connections underneath, which are integral to baseassembly 15. As used herein, “integral electrical connections” and liketerms refer to the orientation of electrical components within baseassembly 15 wherein base assembly 15 physically receives and secures theelectrical components, versus providing a generic housing whereinelectrical components and fasteners are assembled and secured therein.

More specifically, the integral electrical connections beneath removablelid 30 are ribbon terminals 27 (FIGS. 5 and 6) which attach to ribbons28 of solar panel 70, as shown in FIG. 1. The ribbons in the solar panelare an electromechanical means of providing power from the solar cellsto the junction box ribbon terminals. Ribbon terminals 27 provide theelectrical path from panel 70 into junction box 10.

The integral electrical connections beneath diode cover 35 include diodeprinted circuit board assembly module 45 (FIGS. 5 and 8), includingdiodes 46 (FIG. 8). The function of diode assembly module 45 providesthe electrical connection between ribbon terminals 27 and outputterminal 20 while providing the bypass and reverse leakage functionalityrequired to protect the solar panel.

As best shown in FIG. 5, socket assembly 20 is electrically connected todiode assembly module 45. Socket assembly 20 includes O-ring 41 (FIG. 3)and male module plug 40, neither of which are concealed by diode cover35, as shown in FIGS. 2 and 3. As shown in cross section in FIG. 6,module terminal 42 is within male module plug 40 Male module plug 40connects with female module plug 92 of accessory module 90, as shown inFIG. 10.

Accessory module 90 can be a variety of types used in the solar energyindustry. An example of a power electronics type accessory module is amicroinverter from Solantro Semiconductor of Ottawa, Ontario, Canada. Anexample of a supervisory or control type accessory module is an MPPTSPM1258A-S from Solar Power Technologies of Austin, Tex. and/or a boostcontroller STG-MLM2-4 from Tigo Energy of Los Gatos, Calif. An exampleof a standard accessory module is STG-MLM-2 from Shoals TechnologiesGroup of Portland, Tenn., which essentially acts as a place holder butdoes not perform an accessory module function. This inventioncontemplates using modules which are not yet designed or known, forexample arc fault detection, as well as those in development andcommercially available. However, in order to properly interface withjunction box 10, accessory module 90 would have the universalorientation shown in FIGS. 9 and 10, including three clipping assemblies94, and two female module plugs 92. This unique interface between thejunction box and accessory module allows interchangeability of alimitless variety of modules.

Returning to junction box 10 (FIGS. 2 and 7), on either side of eachmale module plug 40 is securing rib 19 which mates with clippingassembly 94 of module 90 (FIG. 9) when module 90 is slid into positionon junction box 10, as shown best in FIG. 10. While clipping assembly 94and securing rib 19 are preferred, other mechanisms for fastening module90 into position on junction box 10 are also possible.

Clipping assembly 94 and securing rib 19 assist in holding module 90 andjunction box 10 together when engaged. In addition, other structures areinvolved with alignment and securing. As shown in FIG. 2, engagementplatform 13 defines grooves 17 that receive corresponding alignment ribs95 on module 90, shown in FIG. 9. As used herein, “engagement platform”shall refer to the general region of junction box 10 that includesgrooves 17, recess 18, and surrounding (unnumbered) planar surface. Inoperation, a user aligns alignment ribs 95 of accessory module 90 withgrooves 17 of junction box 10, and slides accessory module 90 untilfemale module plug 92 engages with male module plug 40. Thepre-engagement alignment is represented in FIG. 10 and engagedorientation is depicted in FIG. 11, with certain structures shown inphantom. Although not obvious from the drawings, grooves 17 are taperedgoing inward, thereby further securing junction box 10 and accessorymodule 90 together. It should be noted that junction box 10 andaccessory module 90, when engaged, are releaseably engaged. As usedherein “releaseably engaged” and similar terms refer to an engagementbetween parts wherein a user can apply reasonable physical force, withor without the necessary use of tools, to engage the parts, andreasonable physical force, with the use of tools, to disengage theparts, with such engagement and disengagement not likely to damage theparts, and with unintentional engagement and disengagement unlikely tooccur in regular use. Recess 18 provides additional air circulation forengaged module 90 in order to reduce hot spots on the solar panel.

FIG. 11 shows an accessory module engaged with junction box 10. In thisorientation, input 96, with wire connector 98 and wire plug 99, is shownon the bottom, and output 97, with wire connector 98 and wire plug 99,is shown on the top. However, it should be noted that accessory modules90 come in a variety of different sizes, and have different functions,and the specific location of input 96 and output 97 is unimportant solong as it can properly interface with junction box 10. Preferably wireplug 99 will be at the distal (relative to accessory module 90) end ofwire connector 98 for output 97, and proximal end of wire connector 98for input 96. In this orientation the proximal end of wire connector 98is “hard wired” into accessory module 90 for output 97. Alternatively,it is possible to employ wire plug 99 and wire connectors 98 at bothends of wire connector 96. Also, it is possible to employ a wire with awire plug 99 or wire connector 98 and a bulkhead connector molded intothe accessory module. Also, it is possible to have the input 96 andoutput 97 both be molded in connectors allowing the customer to controlthe wire length. Preferably wire plug 99 is MC4 from Multi-Contact ofWindsor, Calif.

In use, one could either purchase solar panel 70 with junction box 10already mounted, or retrofit existing solar panel 70 by affixingjunction box 10. With junction box 10 in position, module 90 is engagedwith engagement platform of junction box 10. The same is performed forother solar panels 70 in string 65. The specific modules 90 selected foreach panel 70 depends on the particular circumstances. For example, apanel which is often in the shade might benefit from a boost controller,part number STG-MLM2-4, from Tigo Energy, while a panel that requiresmonitoring or switching capability might benefit from a MPPT accessorymodule, part number SPM1258A-S from Solar Power Technologies.Furthermore, a panel that requires AC output might benefit from amicroinverter accessory module from Solantro Semiconductor. Theresulting module type, or combination of module types, should beselected to optimize the overall productivity of the system with respectto energy generation, cost savings, safety, and so forth. Solar panels70 are grouped into string 65 by connecting output 97 of a downstreamaccessory module 90 to input 96 of immediately upstream accessorymodule. Strings are connected at most downstream point to wire harness80. All the strings connected to one wire harness 80 are collectivelysolar array 60.

Accessory modules 90 are interchangeable by disengaging accessory module90 from junction box 10 (which is affixed to solar panel 70), andengaging a different accessory module. As used herein “interchangeablesolar panel control system” refers to solar panel control system 100with this functionality.

Certain modifications and improvements will occur to those skilled inthe art upon a reading of the foregoing description. By way of example,if one accessory module would suffice for all panels in a string, allpanels except one could employ “standard accessory modules”. It shouldbe understood that all such modifications and improvements have beendeleted herein for the sake of conciseness and readability but areproperly within the scope of the following claims.

We claim:
 1. A method of optimizing the productivity of a solar array,said method comprising the acts of: affixing a first junction box to afirst solar panel, said first junction box including a first output anda first engagement platform including at least one first groove and atleast one first securing rib to engage a first module; engaging saidfirst module with said first groove of said first engagement platform;and securing said first module to said first engagement platformemploying said first securing rib.
 2. The method of claim 1 furtherincluding the acts of: affixing a second junction box to a second solarpanel, said second junction box including a second input, second outputand a second engagement platform including at least one second grooveand at least one second securing rib to engage a second module; engagingsaid second module with said second groove of said second engagementplatform; and securing said second module to said second engagementplatform employing said second securing rib.
 3. The method of claim 2further including the act of connecting said first output to said secondinput.
 4. The method of claim 1 wherein the act of affixing includesadhering.
 5. The method of claim 1 wherein said act of engaging saidfirst module with said first groove of said first engagement platformincludes the act of sliding a raised strip into said first groove. 6.The method of claim 1 wherein said step of securing said first module tosaid first engagement platform employing said first securing ribincludes the step of fastening a first clipping assembly to said firstsecuring rib.
 7. The method of claim 1 further comprising the act ofconnecting a first female module plug to a first male module plug. 8.The method of claim 2 further comprising the act of electricallyconnecting said second output to a wire harness.
 9. The method of claim1 further comprising the act of selecting said first module to maximizethe energy output of said first solar panel.
 10. The method of claim 2further comprising the act of disengaging said first module from saidfirst engagement platform, then engaging a third module.